CN117715136A - Communication system and communication method - Google Patents

Abstract

The invention discloses a communication system and a communication method. A switching is performed which can smooth traffic and improve the utilization efficiency of a network. A communication system comprising a 1 st base station having a 1 st control section and a 2 nd base station having a 2 nd control section, wherein the 1 st control section transmits a handover request to the 2 nd base station when a user terminal needs to handover to the 2 nd base station, the 2 nd control section transmits a handover response including congestion state information in the 2 nd base station to the 1 st base station in response to reception of the handover request, and the 1 st control section transmits a handover instruction including the congestion state information or a data transmission control instruction corresponding to the congestion state information to the user terminal in response to reception of the handover response.

Description

Communication system and communication method

Technical Field

The present disclosure relates to a handover process in a communication system.

Background

A mobile User Equipment (UE) continues to communicate data with the same as before even after handover (non-patent documents 1 and 2). Therefore, even when the handover destination base station is congested, the previous communication is continued, so that the congestion is further serious, and the important communication is adversely affected, and the utilization efficiency of the entire network is also reduced.

Prior art literature

Non-patent literature

Non-patent document 1:3GPP TS 38.300 9.2.3

Non-patent document 2:3GPP TS23.502 4.9.1.3

Disclosure of Invention

An object of one embodiment of the present disclosure is to provide a communication system capable of performing handover that can smooth traffic and improve the utilization efficiency of a network.

One embodiment of the present disclosure is a communication system including a 1 st base station having a 1 st control section and a 2 nd base station having a 2 nd control section, characterized in that,

the 1 st control unit transmits a handover request to the 2 nd base station when a user terminal needs to handover to the 2 nd base station,

the 2 nd control section transmits a handover response including congestion status information in the 2 nd base station to the 1 st base station in response to the reception of the handover request,

the 1 st control unit transmits a handover instruction including the congestion state information or a data transmission control instruction corresponding to the congestion state information to the user terminal in response to the reception of the handover response.

Another mode of the present disclosure is a communication method, including:

a step of sending a switching request to a 2 nd base station when the 1 st base station judges that the user terminal needs to be switched to the 2 nd base station;

a step in which the 2 nd base station transmits a handover response including congestion status information in the 2 nd base station to the 1 st base station in response to the reception of the handover request; and

and the 1 st base station responds to the receiving of the switching response and sends a switching instruction comprising the congestion state information or a data sending control instruction corresponding to the congestion state information to the user terminal.

According to the mode of the present disclosure, traffic can be smoothed and the utilization efficiency of the network can be improved.

Drawings

Fig. 1 is a diagram showing an example of a system configuration of a communication system according to embodiment 1.

Fig. 2 is a diagram showing an example of the switching process.

Fig. 3 is a diagram showing another example of the switching process.

(symbol description)

10: a user terminal; 20a: a base station (handover source base station); 20b: a base station (handover destination base station); 21a, 21b: a wireless device; 22a, 22b: a baseband device; 30: a core network.

Detailed Description

One embodiment of the present disclosure is a communication system including a 1 st base station having a 1 st control section and a 2 nd base station having a 2 nd control section.

When the user terminal needs to be switched to the 2 nd base station, the 1 st control unit of the 1 st base station sends a switching request to the 2 nd base station. Whether or not handover is required can be determined based on the reception intensity of the base station surrounding the user terminal transmitted from the user terminal, and when the reception intensity of the signal from the 2 nd base station exceeds a threshold (the threshold is, for example, the reception intensity of the signal from the 1 st base station), it can be determined that handover is required to the 2 nd base station. The handover request may be sent directly from the 1 st base station to the 2 nd base station, or may be sent from the 1 st base station to the 2 nd base station via another device (e.g., a core network) or process.

The 2 nd control unit of the 2 nd base station transmits a handover response including congestion status information in the 2 nd base station to the 1 st base station in response to the reception of the handover request. The congestion status information may be binary information indicating whether or not congestion has occurred, or may be information indicating the degree of congestion. For example, whether or not congestion occurs or the degree of congestion can be determined based on at least one of the usage rate of the arithmetic processor in the base station, the usage rate of the memory, the usage rate of the communication band, and the usage rate of the radio resource (e.g., resource block). The congestion state information may be information indicating how much data transmission amount the user terminal has communicated after the handover. It is possible to determine the degree of data transmission amount to be used for communication based on the presence or absence of congestion or the degree of congestion in the 2 nd base station. The handoff response may be sent directly from the 2 nd base station to the 1 st base station or from the 2 nd base station to the 1 st base station via other means (e.g., core network) or processing.

The 1 st control unit of the 1 st base station transmits a handover command to the user terminal in response to receiving a handover response from the 2 nd base station. Here, the handover command includes congestion state information or a data transmission control command corresponding to the congestion state information. The data transmission control command may include, for example, information indicating how much data transmission amount the user terminal has communicated after switching to the 2 nd base station. It is possible to determine the degree of data transmission to which communication should be performed based on congestion state information of the 2 nd base station. The handover command may be transmitted directly from the 1 st base station to the user terminal, or may be transmitted from the 1 st base station to the user terminal via another device (e.g., a core network) or a process.

The user terminal switches the connection destination from the 1 st base station to the 2 nd base station in response to a switching instruction from the 1 st base station. After switching from the 1 st base station to the 2 nd base station, the user terminal communicates with the data transmission amount according to the data transmission control instruction or the data transmission amount corresponding to the congestion state information. Further, the user terminal may control data transmission for each communication data according to the priority of the communication data.

According to the above embodiment, after switching to the 2 nd base station, the user terminal can perform communication with the data transmission amount corresponding to the congestion state of the 2 nd base station. Therefore, for example, it is possible to suppress congestion from being serious when congestion occurs in the 2 nd base station, and to smooth traffic of the entire base station and to improve the utilization efficiency.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The configuration of the following embodiment is an example, and the present disclosure is not limited to the configuration of the embodiment.

< embodiment 1 >

(System architecture)

Fig. 1 is a diagram showing an example of a system configuration of a wireless communication system 1 according to embodiment 1. The wireless communication system 1 includes a user terminal 10, base stations 20a, 20b, and a core network 30. The following description will be made with respect to the wireless communication system according to embodiment 1 being a system of a 5G independent system, but the wireless communication system 1 may be a system of any wireless communication system such as a 5G dependent system (4G and 5G sharing), 4G, 3G, or wireless LAN.

The base station 20a includes a wireless device 21a and a baseband device 22a. The radio device 21a performs radio transmission/reception and a lower level function of a radio physical layer, transmits/receives radio waves to/from the user terminal 10, and converts signals to/from analog-to-digital. The baseband device 22a performs functions of radio resource allocation (MAC), retransmission control (RLC), packet ciphering (PDCP), and radio resource management (RRC) of the terminal. Further, the functions of the baseband device 22a can also be installed in a Distributed manner to a plurality of devices (e.g., DU (Distributed Unit) and CU (Central Unit)). The wireless device 21a and the baseband device 22a (or DU and CU) may be provided at physically separate locations or at the same location. The baseband device 22a (or DU and CU) includes an arithmetic processor such as a CPU, a memory (main storage device), an auxiliary storage device, a communication interface, and the like, and executes a computer program by the arithmetic processor to realize the functions. The arithmetic processor is an example of the control unit in the present disclosure.

The base station 20b includes a wireless device 21b and a baseband device 22b. The configuration of the base station 20b is the same as that of the base station 20a, and therefore, the description thereof is omitted. In the following description, when the base station is described in summary, the suffix (a or b) in the symbol may be omitted.

The baseband device 22a of the base station 20a and the baseband device 22b of the base station 20b are connected by an Xn interface. However, according to the base station 20, there are cases where the base station 20 is not directly connected to the baseband device 22 of another base station 20.

The core network 30 performs authentication of the user terminal 10, location management of the user terminal 10, policy control, packet transfer control, establishment of a communication path, and data exchange with an external network. The core network 30 is connected to the base station 20a and the base station 20b by an NG (N2/N3) interface. The core network 30 is also connected to an external network such as the internet or a mobile carrier. In more detail, the core network 30 has the functions of a control plane and a user plane. The functions of the control plane include AMF (Access and Mobility Management Function, access and mobility management functions) which performs connection/mobility management of the user terminal 10, SMF (Session Management Function, session management functions) which performs session management of the user plane, UDM (Unified Data Management ) which manages subscriber information. The user plane is connected to the base station and to an external network, and exchanges user data with the user terminal.

The user terminal 10 is a terminal having a 5G wireless communication function, typically a smart phone terminal, a tablet terminal, or a personal computer. The user terminal 10 includes a wireless communication unit and an information processing unit, and performs wireless communication by connecting to the base station 20 using the wireless communication unit.

(switching Process example 1)

Fig. 2 is a diagram showing an example of the switching process. In this example, it is assumed that the user terminal 10 is handed over from the base station 20a to the base station 20b. Hereinafter, the base station 20a is also referred to as a handover source base station (handover source base station or source base station), and the base station 20b is also referred to as a handover destination base station (handover target base station or target base station).

In addition, fig. 2 shows a handover process in the case where the handover source base station 20a and the handover destination base station 20b can communicate directly (or not via the core network 30).

The handover process shown in fig. 2 starts when the handover source base station 20a determines that the user terminal 10 needs to be handed over to the handover destination base station 20b. A determination as to whether or not a handover is necessary in the handover source base station 20a is made as follows. The user terminal 10 measures the reception strength of a signal transmitted from a neighboring base station, and transmits the measurement result to the currently connected base station (handover source base station 20 a). When the reception intensity of the signal from another base station exceeds the threshold value, the handover source base station 20a determines that a handover to the other base station is necessary. The threshold value is, for example, the reception strength of the signal of the handover source base station 20 a. In a case where the reception intensities of the plurality of base station signals are higher than the threshold, for example, the base station having the highest reception intensity is determined as the base station of the handover destination.

After the start of the Handover process, in step S1, the baseband device 22a of the Handover source base station 20a transmits a Handover Request (Handover Request) to the baseband device 22b of the Handover destination base station 20b.

In step S2, the baseband device 22b of the handover destination base station 20b performs admission control in response to receiving a handover request from the handover source base station 20 a. Admission control is a process of securing radio resources according to the condition of the network and controlling communication according to the condition. The baseband device 22b of the handover destination base station 20b acquires information indicating the state of congestion (hereinafter referred to as congestion state information). The congestion status information may be binary information indicating whether or not congestion has occurred, or may be information indicating the degree of congestion. For example, whether or not congestion occurs or the degree of congestion can be determined based on at least one of the usage rate of the arithmetic processor in the base station, the usage rate of the memory, the usage rate of the communication band, and the usage rate of the radio resource (e.g., resource block). For example, the communication band and the usage rate of radio resources can be obtained as follows. The baseband device 22b saves the result of the allocation of the radio resources in the memory. The baseband device 22b can calculate the usage of the communication band and the usage of the radio resource based on the allocation information stored in the memory. The congestion status information may be the amount of memory/communication band/radio resource used.

In step S3, the baseband device 22b of the handover destination base station 20b transmits a handover response (Handover Request Acknowledgement) including congestion status information to the baseband device 22a of the handover source base station 20 a.

In step S4, the baseband device 22a of the Handover source base station 20a transmits a Handover Command (Handover Command) instructing to Handover to the Handover destination base station 20b to the user terminal 10 in response to the reception of the Handover response. Thereby, the handover source base station 20a causes the user terminal 10 to perform handover. The handover instruction may be, for example, a RRC Reconfiguration message indicating a wireless connection with the handover destination base station 20b. At this time, the baseband device 22a transmits a handover command to the user terminal 10 together with a command related to data transmission after the handover of the user terminal 10 (hereinafter also referred to as a data transmission control command). The data transmission control instruction includes information indicating how much data transmission amount the user terminal 10 communicates after the handover. The handover source base station 20a may include congestion state information in a handover response and transmit the congestion state information to the user terminal 10, so that the user terminal 10 may determine how much data transmission amount should be transmitted after the handover.

In step S5, the user terminal 10 changes the connection destination base station from the base station 20a to the base station 20b in response to receiving the handover instruction from the handover source base station 20 a. After the connection destination is changed, the user terminal 10 performs transmission control so that the user terminal transmits the data transmission amount included in the data transmission control instruction. Alternatively, when the user terminal 10 receives congestion state information, the user terminal 10 performs transmission control so that the user terminal transmits data in accordance with the amount of data transmission corresponding to the congestion state indicated in the congestion state information. When the user terminal 10 needs to suppress the data transmission amount after the handover, the throughput of the communication with the low priority may be reduced or stopped. As an example of a method for reducing throughput, traffic shaping (shaping) is given (buffering packets exceeding the upper band limit and then transmitting them). In addition, traffic policing (dropping packets exceeding the upper band limit) may also be employed depending on the content of the communication. In addition, communication of any one of an image, a moving image, and a sound may be performed by reducing part or all of image quality, sound quality, and frame rate, and sampling rate. Further, the user terminal 10 may consider the priority of the communication data, for example, to reduce the throughput of the low-priority communication for the journal or entertainment without changing the high-priority communication for the autopilot. In addition, conversely, if congestion occurs in the handover source base station 20a and no congestion occurs in the handover destination base station 20b, control may be performed so as to improve throughput and perform communication.

In step S6, the user terminal 10 transmits a Handover Confirm (Handover Confirm) indicating that the Handover is completed to the Handover destination base station 20b. The handover acknowledgement may be, for example, a RRC Reconfiguration Complete message.

Through the above processing, the handover processing of the user terminal 10 from the handover source base station 20a to the handover destination base station 20b is completed.

(switching processing example 2)

Fig. 3 is a diagram showing another example of the switching process. In this example, it is also envisaged that the user terminal 10 is handed over from base station 20a to base station 20b. In this example, the handover source base station 20a and the handover destination base station 20b are not connected by an Xn interface, and cannot directly communicate.

The handover process shown in fig. 3 starts when the handover source base station 20a determines that the user terminal 10 needs to be handed over to the handover destination base station 20b. The determination of whether or not a handover is necessary is the same as that described above, and thus a duplicate explanation is omitted.

When the handover process starts, in step S11, the base band device 22a of the handover source base station 20a transmits a handover request to the core network 30 (Handover Required). Further, the processing can be captured as transmitting a handover request from the handover source base station 20a to the handover destination base station 20b via the core network 30.

In step S12, the core network 30 performs a handover process in response to a handover request from the handover source base station 20 a. The handover process here includes, for example, the selection of an AMF and a UPF.

In step S13, the core network 30 transmits a Handover Request (Handover Request) to the Handover destination base station 20b.

In step S14, the handover destination base station 20b transmits a handover response (Handover Acknowledgment) including congestion status information to the core network 30. The details of the congestion state information are described above, and thus overlapping description is omitted.

In step S15, the core network 30 transmits a Handover Command (Handover Command) including congestion status information to the Handover source base station 20 a.

In step S16, in response to the reception of the handover instruction, the handover source base station generates a data transmission control instruction corresponding to the congestion state information, and transmits the handover instruction including the data transmission instruction to the user terminal 10.

In step S17, the user terminal 10 changes the connection destination base station from the base station 20a to the base station 20b in response to receiving the handover instruction from the handover source base station 20 a. After the connection destination is changed, the user terminal 10 performs transmission control so that the user terminal transmits the data transmission amount included in the data transmission control instruction. This process is the same as described above, and therefore a detailed description thereof is omitted.

In step S18, the user terminal 10 transmits a Handover Confirm (Handover Confirm) indicating that the Handover is completed to the Handover destination base station 20b.

In step S19, the Handover destination base station 20b transmits a Handover notification (Handover Notify) to the core network 30 in response to the reception of the Handover confirmation.

Through the above processing, the handover processing of the user terminal 10 from the handover source base station 20a to the handover destination base station 20b is completed.

(advantageous effects of the present embodiment)

According to the present embodiment, when congestion occurs in the base station of the handover destination, the user terminal performs communication to suppress the data transmission amount after the handover, so that congestion can be suppressed from being serious. In addition, conversely, when congestion occurs in the base station of the handover source and no congestion occurs in the base station of the handover destination, the user terminal can perform communication to improve throughput after the handover, and the network utilization efficiency improves. As described above, according to the present embodiment, the traffic of the entire base station can be smoothed and the utilization efficiency can be improved.

< other modifications >

The above-described embodiment is merely an example, and the present disclosure can be implemented with appropriate modifications within a range not departing from the gist thereof.

The user terminal may perform data transmission in a data transmission amount corresponding to the congestion state of the base station after the handover, and therefore the process of obtaining the data transmission amount after the handover from the congestion state information may be performed in any one of the handover source base station 20a, the handover destination base station 20b, and the user terminal 10.

In the above, the connection between the handover source base station 20a, the handover destination base station 20b, and the core network 30 may be one or more devices.

The processes and units described in the present disclosure can be freely combined and implemented without technical contradiction.

The processing described as 1 apparatus may be performed by a plurality of apparatuses in a shared manner. Alternatively, the processing described as being performed for the different devices may be performed by 1 device. In a computer system, it is possible to flexibly change what hardware configuration (server configuration) is used to realize each function.

The present disclosure can also be realized by providing a computer program having the functions described in the above embodiments installed thereon to a computer having 1 or more processors that read and execute the program. Such a computer program may be provided to a computer through a non-transitory computer readable storage medium that can be connected to a system bus of the computer, or may be provided to the computer through a network. Non-transitory computer readable storage media include, for example, any type of disk such as a magnetic disk (floppy disk (registered trademark), hard Disk Drive (HDD), etc.), optical disk (CD-ROM, DVD disk, blu-ray disk, etc.), read Only Memory (ROM), random Access Memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, optical cards, and any type of medium suitable for storing electronic commands.

Claims (5)

1. A communication system comprising a 1 st base station having a 1 st control section and a 2 nd base station having a 2 nd control section, characterized in that,

the 1 st control unit transmits a handover request to the 2 nd base station when a user terminal needs to handover to the 2 nd base station,

the 2 nd control section transmits a handover response including congestion status information in the 2 nd base station to the 1 st base station in response to the reception of the handover request,

the 1 st control unit transmits a handover instruction including the congestion state information or a data transmission control instruction corresponding to the congestion state information to the user terminal in response to the reception of the handover response.

2. The communication system of claim 1, wherein,

the 2 nd control unit obtains the congestion state information based on at least one of the usage rate of the arithmetic processor, the usage rate of the memory, the usage rate of the communication band, and the usage rate of the radio resource.

3. The communication system of claim 1, wherein,

and after the user terminal is switched to the 2 nd base station, controlling data transmission according to the congestion state information or the data transmission control instruction.

4. A communication system according to claim 3, wherein,

and the user terminal controls data transmission according to the priority of the communication data under the condition of inhibiting the data transmission amount after switching to the 2 nd base station.

5. A method of communication, comprising:

a step of sending a switching request to a 2 nd base station when the 1 st base station judges that the user terminal needs to be switched to the 2 nd base station;

a step in which the 2 nd base station transmits a handover response including congestion status information in the 2 nd base station to the 1 st base station in response to the reception of the handover request; and

and the 1 st base station responds to the receiving of the switching response and sends a switching instruction comprising the congestion state information or a data sending control instruction corresponding to the congestion state information to the user terminal.